### Risk Assessment Revision for 40 CPR Part 61 Subpart W – Radon Emissions from Operating Mill Tailings

Task 3 – Risk Assessment Model

Prepared by:

S. Cohen & Associates 1608 Spring Hill Road, Suite 400 Vienna, VA 22182

under

Contract Number EP-D-10-042 Work Assignment No. 1-06, Task 5

Prepared for:

U.S. Environmental Protection Agency

Office of Radiation and Indoor Air 1200 Pennsylvania Avenue, N.W. Washington, DC 20460

Brian Littleton Work Assignment Manager

August 31, 2010WA 1-04, Task 3 i SC&A – August 31, 2010 TABLE OF CONTENTS

Section Page

Executive Summary..................................

................................................... .................................. iii

1.0 Introduction and Background ........................

................................................... ...................1

2.0 Risk Assessment Models .............................

................................................... .....................2

2.1 AIRDOS, AIRDOS-II, and AIRDOS-EPA .................. ...........................................2

2.2 CAP88..............................................

................................................... .....................3

2.3 GENII with FRAMES..................................

................................................... .........5

2.4 RESRAD-OFFSITE.....................................

................................................... .........7

2.5 MILDOS-AREA........................................

................................................... ...........9

2.6 MEPAS with FRAMES ..................................

................................................... ....12

2.7 AERMOD .............................................

................................................... ..............12

2.8 GASPAR-II..........................................

................................................... ...............13

2.9 GENII-NESHAPS......................................

................................................... .........14

3.0 Detailed Model Evaluations.........................

................................................... ...................15

3.1 Evaluation Criteria................................

................................................... ..............15

3.2 CAP88..............................................

................................................... ...................16

3.3 GENII with FRAMES..................................

................................................... .......20

3.4 RESRAD-OFFSITE.....................................

................................................... .......24

3.5 MILDOS-AREA........................................

................................................... .........27

3.6 MEPAS with FRAMES ..................................

................................................... ....30

4.0 Results and Recommendations ........................

................................................... ...............34

5.0 References.........................................

................................................... ..............................36WA 1-04, Task 3 ii SC&A – August 31, 2010 LIST OF TABLES

Table Page

Table 1. Evaluation Criteria......................

................................................... ................................ 16
Table 2. Summary of Suitability Review for Five Co des Under Evaluation............................... 35WA 1-04, Task 3 iii SC&A – August 31, 2010

EXECUTIVE SUMMARY

The Office of Radiation and Indoor Air (ORIA) promu lgated National Emissions Standards for Hazardous Air Pollutants (NESHAPs) for radon emissi ons from operating uranium mill tailings impoundments (Subpart W) on December 15, 1989. In support of Subpart W, as well as other portions of radiolonuclide NESHAP, ORIA published a Final Environmental Impact Statement (FEIS) and a three volume Background Information Do cument (BID), that provided 1) a detailed description of the Agency’s procedures and methods for estimating radiation dose and risk due to radionuclide emissions to the air, 2) detailed risk estimates for each source of emissions, and 3) detailed economic assessments for each source of emissions.

The purpose of this Work Assignment is to revise th e risk assessment for the NESHAP for Radionuclides from uranium mill tailing facilities. The information developed in this Work Assignment will be used by the Agency in the determ ination of whether the existing standards for Subpart W need revising, and, if so, what may r epresent reasonable revisions to the standard.

As documented in the BID, the FEIS used AIRDOS to c alculate dose and risk to the public. This report reviews the appropriateness of using AIRDOS to calculate individual and population dose and risk. Currently available computer models have been reviewed to determine whether models other than AIRDOS exist for calculating dose and ri sk from the management of uranium byproduct materials from the processing of uranium ores. The atmospheric release risk assessment models reviewed for this Work Assignment were:

● AIRDOS : The AIRDOS computer code was developed at Oak Ri dge National Laboratory (ORNL) to estimate individual (rem/year) and population (man-rem/year) doses resulting from the atmospheric release of rad ionuclides from a nuclear facility. Atmospheric dispersion and surface deposition of re leased radionuclides are estimated as

a function of direction and distance from a nuclear power plant or fuel-cycle facility, and doses to man through inhalation, air immersion, exp osure to contaminated ground, food ingestion, and water immersion are estimated in the surrounding area. Radionuclide concentrations in food products are estimated from the output of the atmospheric transport model using the terrestrial transport mod el described in U.S. Nuclear Regulatory Commission (NRC) Regulatory Guide 1.109. Annual doses are estimated for total body, GI tract, bone, thyroid, lungs, muscle, kidneys, liver, spleen, testes, and

ovaries.

● CAP88 : The CAP88 (which stands for Clean Air Act Assess ment Package - 1988) computer model is a set of computer programs, datab ases and associated utility programs

for estimation of dose and risk from radionuclide e missions to air. CAP88 is composed

of modified versions of AIRDOS-EPA and DARTAB. CAP 88-PC Version 3 incorporates dose and risk factors from Federal Gui dance Report 13. CAP88-PC is a U.S. Environmental Protection Agency (EPA) approved system for demonstrating compliance with 40 CFR 61 Subpart H, the Clean Air Act standard which applies to U.S. Department of Energy (DOE) facilities that emit rad ionuclides to air. EPA will provide the latest version of CAP88 to SC&A for evaluation, otherwise, SC&A will evaluate Revision 3, currently available from the EPA websit e: http://www.epa.gov/radiation/assessment/CAP88/

.WA 1-04, Task 3 iv SC&A – August 31, 2010

● GENII : The GENII system, developed by the Pacific North west National Laboratory (PNNL), includes the capabilities for calculating r adiation doses following chronic and acute releases. Radionuclide transport via air, wa ter, or biological activity may be considered. Air transport options include both puf f and plume models. Building wake effects can be included in acute atmospheric releas e scenarios. The code provides risk estimates for health effects to individuals or popu lations; these can be obtained using the code by applying appropriate risk factors to the ef fective dose equivalent or organ dose. In addition, GENII Version 2 uses cancer risk facto rs from Federal Guidance Report 13 to estimate risk to specific organs or tissues.

● RESRAD : RESRAD is a computer model developed by Argonne National Laboratory to

estimate radiation doses and risks from RESidual RA Dioactive materials. Since 1989, RESRAD has been used widely by DOE, its operations and area offices, and its contractors for deriving limits for radionuclides i n soil. RESRAD has also been used by EPA, U.S. Army Corps of Engineers, NRC, industrial firms, universities, and foreign government agencies and institutions.

● MILDOS-AREA : The Argonne National Laboratory also developed M ILDOS-AREA, a computer code that calculates the radiological dose commitments received by individuals and the general population within an 80-km radius o f an operating uranium recovery facility. The transport of radiological emissions from point and different area sources is predicted with a sector-averaged Gaussian plume dis persion model. Mechanisms such as radioactive decay, plume depletion by deposition, i n-growth of decay products, and resuspension of deposited radionuclides are include d in the transport model. Alterations in operation throughout the facility's lifetime can be accounted for in the input stream. The exposure pathways considered are: inhalation; external exposure from groundshine and cloud immersion; and ingestion of vegetables, m eat, and milk. Dose commitments are calculated primarily on the basis of the recomm endations of the International Commission on Radiological Protection (ICRP). Only airborne releases of radioactive materials are considered in MILDOS-AREA; releases t o surface water and to groundwater are not addressed in MILDOS-AREA. MILD OS-AREA is a multi-purpose code that can be used to evaluate population doses for NEPA assessments, maximum individual doses for predictive 40 CFR 190 complian ce evaluations, or maximum offsite air concentrations for predictive evaluations of 10 CFR 20 compliance.

● MEPAS : Multimedia Environmental Pollutant Assessment Sy stem (MEPAS), developed by the Pacific Northwest Laboratory (PNL) , is a suite of integrated impact assessment software comprising physics-based fate a nd environmental transport models of air, soil, and water media. MEPAS simulates the release of contaminants from a source; transport through the air, groundwater, sur face water, and/or overland pathways; and transfer through food chains and exposure pathw ays to the exposed individual or population. For human health impacts, risks are co mputed for carcinogens and hazard quotients for noncarcinogens.

● AERMOD : AERMOD was developed by the AERMIC (American Met eorological Society (AMS)/U.S. Environmental Protection Agency (EPA) Regulatory Model Improvement Committee) as a state-of-the-practice G aussian plume dispersion model whose formulation is based on planetary boundary la yer principles. The AERMOD model utilizes a probability density function and t he superposition of several GaussianWA 1-04, Task 3 v SC&A – August 31, 2010

plumes to characterize the distinctly non-Gaussian nature of the vertical pollutant distribution for elevated plumes during convective conditions; otherwise the distribution is Gaussian. Also, nighttime urban boundary layers (and plumes within them) have the turbulence enhanced by AERMOD to simulate the influ ence of the urban heat island. The AERMOD model is applicable to rural and urban a reas, flat and complex terrain, surface and elevated releases, and multiple sources (including point, area and volume sources).

Each of the above computer models was described and discussed in detail, including the results of any benchmarks that were performed between the m odels. During this phase of the review, four of the models (AIRDOS, GASPAR, GENII-NESHAPS, and AERMOD) were eliminated from further evaluation. Next, a detailed evaluati on of the remaining five atmospheric release risk assessment models was performed. The criteria used in the detailed evaluation are shown in

Table ES-1. To account for the fact that not all o f the criteria were considered to be of equal importance, weight factors were assigned to each of the criteria, as shown in Table ES-1.

Table ES-1. Evaluation Criteria

Evaluation Criteria Weight

Factor Exposure Pathways Modeled 2 Population Dose/Risk Capability 2

Dose Factors Used 1.75

Risk Factors Used 1.75 Meteorological Data Processing 1.5

Source Term Calculations 1.5

Verification and Validation 1.25 Ease of Use/User Friendly 1.25

Documentation 1 Sensitivity Analysis Capability 1 Probabilistic Analysis Capability 1

The results of the detailed evaluation are shown in Table ES-2.

Table ES-2. Evaluation Results

Evaluation Criteria Score

RESRAD-OFFSITE 66.25

CAP88 65.5

GENII 61.75

MEPAS 57

MILDOS-AREA 48

As Table ES-2 shows, RESRAD-OFFSITE was the highest scoring of the five codes, narrowly edging out CAP88. However, it is recommended that CAP88, and not RESRAD-OFFSITE, be used to perform the dose and risk calculations requ ired for this Work Assignment. The reasons

for this recommendation include:WA 1-04, Task 3 vi SC&A – August 31, 2010

• RESRAD-OFFSITE does not include the ability to perf orm population dose and risk estimates, which means that the RESRAD-OFFSITE resu lts would need to be supplemented with population dose and risk estimate s from another source. CAP88, on the other hand, is specifically designed to assess radiological emissions to the public.

• The major area where CAP88 is lacking is sensitivit y and probability analyses. For this Work Assignment, it is not anticipated that sensiti vity or probability analysis will play a major role.

• RESRAD-OFFSITE incorporates CAP88 air dispersion mo deling, which means that there are no significant technical differences betw een the two codes for the purpose of this Work Assignment.

• CAP88 was developed as a predecessor to AIRDOS whic h was the original code used in the evaluation of mill tailing impoundments during the development of the NESHAPs for

radon emissions in 1989.WA 1-04, Task 3 1 SC&A – August 31, 2010

1.0 INTRODUCTION AND BACKGROUND

The Office of Radiation and Indoor Air (ORIA) promu lgated National Emissions Standards for Hazardous Air Pollutants (NESHAPs) for radon emissi ons from operating uranium mill tailings impoundments (Subpart W) on December 15, 1989. In support of Subpart W, as well as other portions of radiolonuclide NESHAPs, ORIA published a Final Environmental Impact Statement (FEIS) and a three volume Background Information Do cument (BID) that provided 1) a detailed description of the Agency’s procedures and methods for estimating radiation dose and risk due to radionuclide emissions to the air, 2) detailed risk estimates for each source of emissions, and 3) detailed economic assessments for each source of emissions.

The purpose of this Work Assignment is to revise th e risk assessment for the NESHAPs for radionuclides from uranium mill tailing facilities. The information developed in this Work Assignment will be used by the Agency in the determ ination of whether the existing standards for Subpart W need revising, and, if so, what may r epresent reasonable revisions to the standard.

As documented in the BID, the FEIS used AIRDOS to c alculate dose and risk to the public. This report reviews the appropriateness of using AIRDOS to calculate individual and population dose and risk. Currently available computer models have been reviewed to determine whether models other than AIRDOS exist for calculating dose and ri sk from the management of uranium byproduct materials from the processing of uranium ores. The report examines the applicability

of available models to evaluate radon emissions fro m operating mill tailings impoundments. By evaluating the various modeling codes against a set of predetermined criteria (outlined in Section 3), it will be determined which code is mos t suitable for the purposes of determining current dose and risk conditions at these operating sites. The modeling codes will be considered based on their applicability to the problem, whethe r current analytical methods are employed (such as dose and risk factors), the ability to pro cess population and meteorological data, to what extent the code is documented/validated, and finall y, how user friendly and intuitive the code is.

The report is organized into three main sections (S ections 2-4): Section 2 provides a description of the computer models that were evaluated, Section 3 presents the evaluation criteria and results of the evaluation for the main codes selected, and the final section summarizes the results of the

evaluation and recommends which code should be used for the individual and population dose and risk analysis, which will be performed as part of Task 4 of this Work Assignment.WA 1-04, Task 3 2 SC&A – August 31, 2010

2.0 RISK ASSESSMENT MODELS

2.1 AIRDOS, AIRDOS-II, and AIRDOS-EPA

The AIRDOS computer code was developed at Oak Ridge National Laboratory (ORNL) to estimate individual (rem/year) and population (man- rem/year) doses resulting from the atmospheric release of radionuclides from a nuclear facility. Atmospheric dispersion and surface deposition of released radionuclides are estimated as a function of direction and distance from a nuclear power plant or fuel-cycle facility, and dos es to man through inhalation, air immersion, exposure to contaminated ground, food ingestion, an d water immersion are estimated in the surrounding area. Radionuclide concentrations in f ood products are estimated from the output of the atmospheric transport model using the terrestri al transport model described in U.S. Nuclear Regulatory Commission (NRC) Regulatory Guide 1.109. Annual doses are estimated for total body, GI tract, bone, thyroid, lungs, muscle, kidne ys, liver, spleen, testes, and ovaries. For additional information regarding the development of AIRDOS, refer to Moore 1975, Moore 1977, and Moore, et al. 1979.

Of particular interest to this Work Assignment, in 1978, the NRC used AIRDOS-II to perform a detailed analysis of the radiological impact of the Irigaray project of solution mining (in situ leaching) operations involving uranium ore deposits in Johnson County, Wyoming. The results of the NRC’s AIRDOS-II analysis are presented in th e Final Environmental Statement for the Irigaray project (NUREG-0481).

For the NESHAPs for Radionuclides, EIS risk assessm ent (EPA/520/1-89-005), EPA used

AIRDOS-EPA to calculate environmental concentration s resulting from radionuclide emissions into air. The results of the AIRDOS-EPA analysis w ere estimates of air and ground surface radionuclide concentrations; intake rates via inhal ation of air; and ingestion of radioactivity via meat, milk, and fresh vegetables. The AIRDOS-EPA c alculated concentration and intake rates, as well as other parameters (such as particle size, respiratory clearance class, and gastrointestinal absorption factor), were passed on to the DARTAB co mputer program for dose and risk assessments. The DARTAB computer program provides an estimate of the impact of radionuclide emissions by combining information on the amounts of radionuclides inhaled and/or ingested with dosimetric and health effect d ata for a given quantity of each radionuclide. In addition to the AIRDOS-EPA provided data, the DA RTAB NESHAPs for Radionuclides, EIS

assessment utilized dosimetric and health effect da ta that were calculated by RADRISK. The RADRISK program calculates the dose rate to organs resulting from the inhalation or ingestion of a given quantity of a radionuclide. The organ d ose rates are then processed by RESRAD to calculate the risk of fatal cancer to a cohort of p eople. For approximately 500 radionuclides, the calculated risks (i.e., the probability of prematur e death for a member of the cohort due to inhalation or ingestion of a given quantity of each radionuclide) are written to a data file by RADRISK so that they can be accessed by other compu ter programs (e.g., DARTAB).

On October 31, 1989, under 40 CFR Part 61, NESHAPs, the EPA issued the final rules for radionuclide emissions to air. AIRDOS-EPA, DARTAB, and the RADRISK dose and risk

factors were combined into the Clean Air Act Assess ment Package-1988 (CAP88) and used toWA 1-04, Task 3 3 SC&A – August 31, 2010

generate risk estimates for the risk assessment sup porting this rule. With the issuance of CAP88, AIRDOS-EPA, DARTAB, and RADRISK ceased to exist as standalone computer programs.

CAP88 is discussed below.

2.2 CAP88

As stated above in the AIRDOS discussion, the CAP88 was developed in 1988 from the AIRDOS, RADRISK, and DARTAB computer programs. The initial version of CAP88 ran on large mainframe computers at ORNL, however, in the late 1980s, the EPA and the U.S. Department of Energy (DOE) began a cooperative proj ect to produce a personal computer version of CAP88 — CAP88-PC, which was released in March 1992. CAP88 implements the NRC’s Regulatory Guide 1.109 methodology for calcul ating doses from the terrestrial food pathways.

Among the modifications and enhancements made to CA P88 during its conversion to CAP88-PC

include the fact that CAPP88-PC estimates risk as w ell as dose. CAP88-PC was modified to perform either “Radon-only” or “Non-Radon” runs, to conform to the format of the 1988 Clean Air Act NESHAPs Rulemaking. “Radon-only” assessmen ts, which only have Rn-222 in the source term, automatically include working level ca lculations; all other source terms ignore working levels. Also, the organs and weighting fac tors are modified to follow the ICRP 26/30 Effective Dose Equivalent calculations, which elimi nates flexibility on specifying organs and weighting factors. In February 1992, CAP88-PC, Ver sion 2.0 was approved for demonstrating compliance with 40 CFR Part 61 “Subpart H – Nationa l Emission Standards for Emissions of Radionuclides Other Than Radon from Department of E nergy Facilities”.

In March 2000, Version 2 of CAP88-PC was issued. C AP88-PC, Version 2 provided a framework for developing inputs to perform full-fea tured dose and risk assessments in a Windows environment, as well as some minor changes to the DOS version. Like Version 1.0, Version 2.0 of CAP88-PC was approved for demonstrat ing compliance with 40 CFR Part 61 in

October 1999.

In May 2002, CAP88-PC, Version 2.1 was issued. Ver sion 2.1 included changes in installation and operating environment (e.g., improvements in th e Windows code error handling), as well as changes to increase the programs flexibility (e.g., site-specific humidity, site-specific distance and sector, and higher radionuclide limit).

In August 2002, CAP88-PC, Version 3.0 was issued. Version 3.0 is a significant update to

Version 2.1. Some of the Version 3 enhancements in clude:

• Incorporated the dose and risk factors from Federal Guidance Report (FGR) 13, in place of the RADRISK data that was used in previous versi ons

• Expansion of the nuclide database to 825 nuclides w hich include all the FGR 13-based decay chains

• Eliminated calculation of genetic effects

• Dose factors are now a function of chemical form wh ere specified in FGR 13WA 1-04, Task 3 4 SC&A – August 31, 2010

• Organ dose equivalent is calculated for 23 internal organs, mortality risk is calculated for

15 cancer sites

• Internal absorption class terminology updated to F (fast), M (medium), and S (slow)

• All particulates are assumed to be 1.0 micron in ac cordance with the FGR 13 model, with the exception of gases and vapor which are ‘0’

• Radionuclide transfer factors have been updated to reflect NCRP Report #123

• Version 3 has added (though not fully implemented) age dependent dose factors, cancer morbidity risk factors, additional pathways such as drinking water ingestion and external exposure from multiple depths of soil

In 1994 Maheras, et al. performed a benchmarking of CAP88 to the GENII computer program. The following is a summary of their results:

The results of the benchmark tests were within the 95% acceptance region specified in the test protocol. CAP-88 was found to over-predic t effective dose equivalent relative to GENII for elevated releases, largely because CAP-88 calculates a larger atmospheric dispersion factor (chi/Q) than does GENII using the same meteorological data. However, CAP-88 consistently under-predicted effective dose equivalent relative to GENII for ground-level releases. This was because CAP-88 acc ounts for the processes of plume depletion by dry and wet deposition while GENII doe s not account for these processes. The effect of depletion was tested and found to be most important for a ground-level release of a highly depositing species such as radi oiodine which implies that acceptable

benchmark results would be difficult to obtain for a highly depositing species.

ANL/ES-161 presents the results from benchmarking C AP88 against MILDOS-AREA. The

ANL/ES-161 results are summarized below in the MILD OS-AREA discussion (Section 2.5).

CAP88-PC was benchmarked against RESRAD-OFFSITE and the results are presented in ANL/EVS/TM/06-3, Section 3. Four areas were tested :

• Simple dispersion model – For the simple dispersion model, ANL/EVS/TM/06-3 reported that the agreement between CAP88-PC and RE SRAD-OFFSITE was good, and that the differences for all distances were approxi mately 6% or less, except at 100 meters

where a 13% difference was found. ANL/EVS/TM/06-3 concluded that these differences

can be attributed to variations in the vertical dis persion coefficient and the actual area source methodology.

• Dry deposition – For dry deposition, good agreement between the codes was obtained for receptor distances of less than 10,000 meters. Aft er 10,000 meters, the RESRADOFFSITE air concentration is about 3 times larger t han that from CAP88-PC.

• Wet deposition – Aside from the 100-meter location, RESRAD-OFFSITE and

CAP88-PC results remain within 10% of each other ou t to a distance of approximately 3,000 meters. Thereafter, the CAP88-PC results bec ome increasingly larger than the RESRAD-OFFSITE results up to 80,000 meters.WA 1-04, Task 3 5 SC&A – August 31, 2010

• Plume rise – The RESRAD-OFFSITE and CAP88-PC plume rise results agree to within about 15% or less for receptor distances of less th an 500 meters. After 500 meters, plume rise has negligible differences between the two pro grams.

In DOE/ORO-2033, MEPAS was benchmarked against RESR AD-OFFSITE. Because CAP88 is linked to RESRAD to perform atmospheric dispersion calculations, DOE/ORO-2033 was in effect a benchmarking of CAP88 against MEPAS. Two comparisons were performed:

• Air concentration – A constant emission of thorium- 228 was assumed. The air concentration comparisons show that nearly identica l results are obtained with the models

for the direct air release scenario.

• Deposition – The soil concentrations at 1 km result ing from deposition from the thorium228 plume over the 10 years. The deposition compar isons show the models give approximately the same results. At the 1.0-km dist ance, the magnitude of the predicted deposition rates reflects mainly the predicted air concentrations and the deposition

velocities.

Finally, Lehto, et al. (2000) state that the milk c ow and meat cattle densities are entered into CAP88 in units of “per square kilometer, but this i s erroneous according to [B. Parks].” If CAP88 is to be used, then the correct units for ent ering milk cow and meat cattle densities will

need to be used.

2.3 GENII with FRAMES

The Hanford Environmental Dosimetry Upgrade Project was undertaken to incorporate the internal dosimetry models recommended by the Intern ational Commission on Radiological Protection (ICRP) into updated versions of the envi ronmental pathway analysis models used at Hanford. The resulting second generation of Hanfor d environmental dosimetry computer codes was compiled in the Hanford Environmental Dosimetry System (Generation II, or GENII). The purpose of this coupled system of computer codes wa s to analyze environmental contamination resulting from acute or chronic releases to, or ini tial contamination of, air, water, or soil. This was accomplished by calculating radiation doses to individuals or populations. The GENII system was designed to provide a state-of-the-art, technically peer-reviewed, documented set of programs for calculating radiation doses from radio nuclides released to the environment.

GENII was designed to include the capabilities: 1) for calculating radiation doses for acute releases, with options for annual dose, committed d ose, and accumulated dose; 2) for calculating the same types of doses from chronic releases; and 3) for evaluating exposure pathways including direct exposure via water (swimming, boat ing, and fishing), soil (surface and buried sources), air (semi-infinite cloud and finite cloud geometries), inhalation pathways, and ingestion pathways.

The GENII release scenarios include acute releases to air from ground level or elevated sources, or to water; chronic releases to air from ground le vel or elevated sources, or to water; and initial

contamination of soil or surfaces. GENII accounts for source term variations, including decay of radionuclides to the start of the exposure scenario , input of total radioactivity or specifiedWA 1-04, Task 3 6 SC&A – August 31, 2010

fractions, and input of measured concentrations in specified environmental media. Air transport options include both puff and plume models. Buildi ng wake effects can be included in acute atmospheric release scenarios. Interfaces were pro vided for external calculations of atmospheric dispersion, geohydrology, biotic transport, and sur face water transport. The model used by

GENII to estimate radionuclide concentration in edi ble plant portions considers uptake from two pathways: direct deposition and absorption through roots from soil. The model is a variant of that prepared for the NRC for use in Regulatory Gui de 1.109. Target populations were identified by distance and direction for individuals, populati ons, and for intruders into contained sources. The code provides risk estimates for health effects to individuals or populations; these can be obtained using the code by applying appropriate ris k factors to the effective dose equivalent or organ dose. In addition, GENII, Version 2 implemen ts these models plus those of ICRP Publications 56 through 72 and the related risk fac tors published in Federal Guidance Report 13.

The original version of GENII, released in 1988, wa s composed of seven interrelated computer

codes and their associated data libraries. The con nection between the codes is through data transfer files, i.e., the output of one code is sto red in a file that can be read by the next code in the system. The environmental transport calculations w ere performed in ENV, while the individual and population doses were calculate in DOSE. The c ode DITTY was used to calculate long-term (>10,000 years) exposures. External and internal d ose factors were calculated by the EXTDF and INTDF codes. Finally, two data preparation cod es were provided: APPRENTICE and ENVIN. The experienced GENII user could stop the p rocess at any point and edit the intermediate data transfer files to obtain specific information on the processes occurring or on

intermediate results.

For maximum flexibility, the most current version o f GENII, Version 2.10, has been divided into several interrelated, but separate, exposure and do se calculations consisting of four independent atmospheric models, one surface water model, three independent environmental accumulation models, one exposure module, and one dose/risk modu le, each with a specific user interface. GENII, Version 2.10 operates within the Framework f or Risk Analysis in Multimedia Environmental System (FRAMES). FRAMES allows the a ddition of other computer modules to the GENII system. For example, GENII does not expl icitly include modules for performing groundwater transport calculations, however, with F RAMES, groundwater transport models can be incorporated into the GENII model. Additional i nformation on FRAMES is provided in

Section 2.3.1.

In 1994, Maheras, et al. performed a benchmarking o f CAP88 to the GENII computer program. The results of this benchmark are presented above i n Section 2.2.

ANL/EAD/TM-24 benchmarked GENII against RESRAD. Un fortunately, the ANL/EAD/TM-24 benchmarking was mostly interested in comparing the two codes’ ability to analyze ground contamination scenarios, rather than air release scenarios, so the

ANL/EAD/TM-24 results are of little value to this W ork Assignment.WA 1-04, Task 3 7 SC&A – August 31, 2010

2.3.1 FRAMES

Over the past 35 years, medium specific models have been and will continue to be developed in an effort to understand and predict environmental p henomena, including fluid-flow patterns (e.g., groundwater, surface water, and air), contaminant m igration and fate, human or wildlife exposures, impacts from specific toxicants to speci fic species and their organs, cost-benefit analyses, impacts from remediation alternatives, et c. The DOE Office of Environmental Management (DOE-EM), the EPA Office of Research and Development (EPA-ORD), and the EPA Office of Radiation and Indoor Air (EPA-ORIA) h ave realized the need for a common platform to access and link these medium-specific m odels. The objective is to 1) combine existing models and approaches that assess hazardou s and radioactive releases in and their impacts on the environment into a single framework and 2) structure the framework into a flexible and versatile, user-friendly tool that mee ts the needs of both organizations. FRAMES has been developed by Pacific Northwest National La boratory (PNNL) to meet this need.

FRAMES is a software platform for selecting and imp lementing environmental software models for risk assessment and management problems. Curre ntly, MEPAS and GENII are available in FRAMES, while other codes are scheduled to be inclu ded in the future. The FRAMES User Interface (FUI) allows users to link, select, and i nteract with environmental codes for environmental and human health analyses. The FUI i s used to: create, access, save, and exit Global Input Data (GID) files; select module types and connections; run the scenario models in sequence; and perform several other functions. In this manner, FRAMES can be used to select the most desirable features of specific models and link them together into a superior single integrated model. For example, the output from a s ource term generation code (e.g., GALE) could be linked with a sophisticated atmospheric tr ansport code (e.g., AERMOD) which is linked to an exposure pathways evaluation model (e.g., CAP 88).

Unfortunately, as stated above, at this time only M EPAS and GENII are available in FRAMES, and since these two programs perform similar calcul ations, it’s not clear that there is any advantage to the current FRAMES. Also, in order to take advantage of future FRAMES capabilities, the process necessary to setup and ru n a single model (i.e., GENII or MEPAS) within FRAMES is more complicated than to setup and run the same model outside of FRAMES (at least to the authors of this report). For thes e reasons, a wait-and-see attitude has been taken with regard to FRAMES, which will also influence th e selection of GENII and MEPAS for use in this Work Assignment, since they are only availa ble within FRAMES.

2.4 RESRAD-OFFSITE

RESRAD is a computer model developed by Argonne Nat ional Laboratory to estimate radiation

doses and risks from RESidual RADioactive materials . Since its first release in 1989, RESRAD has been used widely by DOE, its operations and are a offices, and its contractors for deriving

limits for radionuclides in soil. RESRAD has also been used by the EPA, U.S. Army Corps of Engineers, NRC, industrial firms, universities, and foreign government agencies and institutions. RESRAD evaluates the radiological dose and excess c ancer risk to an individual who is exposed while residing and/or working in an area where the soil is contaminated with radionuclides.WA 1-04, Task 3 8 SC&A – August 31, 2010

RESRAD-OFFSITE code is an extension of the original RESRAD code. The most current version is RESRAD-OFFSITE Version 2.6, which was re leased July 7, 2010.

RESRAD-OFFSITE considers initial radiological conta mination in soil in settings ranging from a clean cover layer on top of it to up to five part ially saturated layers below it. The code has a capability to model the radiation exposure of an in dividual who spends time directly above the primary contamination (onsite) and in the vicinity of the primary contamination (offsite).

Nine exposure pathways are considered in RESRAD-OFF SITE: direct exposure from contamination in soil, inhalation of particulates a nd radon, ingestion of plant foods, ingestion of meat, ingestion of milk, ingestion of aquatic foods , ingestion of water, and incidental ingestion of soil. By selecting different pathways, RESRAD-OFFS ITE can be used to simulate various exposure scenarios, including Rural Resident Farmer , Urban Resident, Worker, and

Recreationist.

The RESRAD Users Manual and the RESRAD-OFFSITE webs ite ( http://web.ead.anl.gov/

resrad/home2/offsite.cfm ) state that RESRAD-OFFSITE “links with the CAP88 c omputer code for performing air dispersion calculations”.

Regarding radon, the RESRAD-OFFSITE Users Manual in dicates that it uses the same model as RESRAD for onsite exposures, and the RESRAD Users M anual describes the radon model as:

The primary environmental parameters that can influ ence the dispersion of radon in outdoor air are meteorological conditions, such as wind speed and stability class. The calculation of outdoor radon concentrations by usin g all these parameters requires a comprehensive atmospheric dispersion code such as t he MILDOS-AREA code (...). These extensive computations are not practical for the purposes of the RESRAD code, because the average radon concentration outdoors on top of a radium-contaminated area would be dependent on the size of the contaminated area and the average wind speed, and it would not be very sensitive to other meteorologi cal parameters.

In addition, RESRAD-OFFSITE includes radon transpor t to an offsite location. Radon offsite “concentrations are computed [by RESRAD-OFFSITE] fr om the flux of radon released from the primary contamination and the in-growth and decay-a djusted Chi/Q factors for radon and its short-lived progeny, computed from the atmospheric transport model.” It is not clear from this if RESRAD-OFFSITE uses the CAP88 equilibrium fraction method for estimating the short-lived radon progeny concentrations (see Section 2.5), or if the progeny concentrations are calculated directly from the Bateman equation.

RESRAD-OFFSITE was benchmarked against CAP88-PC and the results are presented in ANL/EVS/TM/06-3, Section 3, and summarized above in Section 2.2.

ANL/EAD/TM-24 benchmarked RESRAD against GENII. Un fortunately, the ANL/EAD/TM-24 benchmarking was mostly interested in comparing the two codes’ ability to analyze ground contamination scenarios, rather than air release scenarios, so the

ANL/EAD/TM-24 results are of little value to this W ork Assignment.WA 1-04, Task 3 9 SC&A – August 31, 2010

In 2008, as part of their verification of MILDOS-AR EA, Argonne National Laboratory (ANL) compared the MILDOS-AREA air dispersion component w ith that of the RESRAD-OFFSITE code. The results of that comparison are summarize d below in Section 2.5.

In DOE/ORO-2033, RESRAD-OFFSITE was benchmarked aga inst MEPAS. Because CAP88 is linked to RESRAD to perform atmospheric dispersion calculations, DOE/ORO-2033 was, in effect, a benchmarking of CAP88 against MEPAS. The DOE/ORO-2033 results are summarized

above in Section 2.2.

2.5 MILDOS-AREA

MILDOS estimates impacts from radioactive emissions from uranium milling facilities. These impacts are presented as dose commitments to indivi duals and the regional population within an 80-km radius of the facility. Only airborne releas es of radioactive materials are considered: releases to surface water and to groundwater are no t addressed in MILDOS, i.e., liquid exposure pathways are not treated by MILDOS. Exposure pathw ays of concern are assumed to be inhalation of airborne radioactive material, ingest ion of vegetables, meat, and milk contaminated via deposition, and external exposure to radiation emitted by airborne activity and activity deposited on ground surfaces. MILDOS can be used t o evaluate population doses for NEPA assessments, maximum individual doses for predictiv e 40 CFR 190 compliance evaluations, or maximum offsite air concentrations for predictive 1 0 CFR 20 compliance evaluations.

In the mid-1970s, UDAD (Uranium Dispersion And Dosi metry) was developed by ANL for the NRC to provide comprehensive estimates of the poten tial radiation dose rate and dose to the standard man and the standard population in the vic inity of a uranium processing facility, such as a uranium mill or mine. UDAD was applied, initiall y in 1976, for the assessment of the radiological impact of the Bear Creek uranium minin g and milling project and was later expanded for generic evaluation of uranium milling in the United States. UDAD is documented

in NUREG/CR-0553.

In 1981, MILDOS (NUREG/CR-2011) was developed by Pa cific Northwest Laboratory (PNL) from UDAD. The models and assumptions on which the MILDOS program was based are described in the NRC Regulatory Guide 3.51 and NURE G/CR-0553. Models were included in MILDOS to consider both point sources (stacks, vent s) and area sources (ore pads, tailing areas).

Particulate release is limited to radionuclides of the uranium-238 decay series (i.e., U-238, Th-230, Ra-226, and Pb-210). Other radionuclides w ithin the U-238 series are implicitly accounted for under the secular equilibrium assumpt ion. Gaseous release was limited to consideration of Rn-222, plus ingrowth of daughters . The dose to exposed individuals is calculated for comparison with requirements of both 40 CFR 190 and 10 CFR Part 20. Ingestion

dose factors were based on ICRP Publication 2 and 1 0A, inhalation dose factors were calculated in accordance with the ICRP’s Task Group on Lung Dy namics’ lung model (TGLM) (ICRP 1966 and 1972), and external dose factors were dire ctly taken from Hones and Soldat (1977).

In 1989, Argonne National Laboratory developed the MILDOS-AREA code (ANL/ES-161) to provide enhanced capability to compute doses from l arge-area sources and to incorporate changes in methods for dosimetry calculations (ICRP 1979). The revised program was designedWA 1-04, Task 3 10 SC&A – August 31, 2010

for use on IBM or IBM-compatible personal computers . MILDOS-AREA considers the same radionuclides as MILDOS. A validation study of MIL DOS-AREA was conducted using

measured Rn-222 concentration and flux data from th e Monticello, Utah uranium mill tailings impoundment. The results of this study demonstrate d that use of MILDOS-AREA can result in generally good agreement between model-generated an d measured Rn-222 concentrations.

In 1997, MILDOS-AREA computer code was further upda ted by ANL to incorporate dose conversion factors derived by the ICRP recommendati ons of 1978, and to make it compatible with the January 1, 1994, revision of 10 CFR Part 2 0. The 1997 update also created an example problem for applying MILDOS-AREA to in-situ leach f acilities.

In 1998, MILDOS-AREA was provided with the user-fri endly software interface. This graphical user interface (GUI) is simple and easy to use and allows MILDOS-AREA to run under the Windows operating system.

ANL/ES-161, Appendix B presents a comparison betwee n MILDOS-AREA and CAP88 1

. Calculated Rn-222 concentrations and working levels calculated by the two codes at 12 distances and four directions were compared. The Rn-222 conc entrations calculated by the two codes are in very good agreement for distances greater than a bout 1 km for the release point, and, at closer distances, the CAP88 calculated Rn-222 concentratio ns are as much as 50% higher than the

MILDOS-AREA concentrations.

However, for the working level calculations, the re sults are much different. Near the source (e.g., <1 km), the CAP88 calculated working levels are much greater (sometimes greater than an order of magnitude) than the MILDOS-AREA calculated working levels. At larger distances (e.g., 5 to 10 km), the working levels calculated b y the two codes are about the same, and at even larger distances (e.g., 70 km), the MILDOS-AREA cal culated working levels are greater (by up to about 50%) than the CAP88 calculated working lev els. The reason for this is the different approaches used by the two codes to calculate radon decay product concentrations. CAP88 uses a fixed linear interpolation of the decay product e quilibrium fraction beginning at 0.267 at 150 meters and reaching a final equilibrium fraction of 0.698 at 19,551 meters. MILDOS-AREA, on the other hand, directly calculates the radon daugh ter concentrations based on the Rn-222 concentration and plume travel time. The ANL/ES-16 1, Appendix B results indicate that radon daughter equilibrium factors are significantly less than 27% at small distances and greater than 70% at very large distances from the source.

In 2008, ANL prepared a limited-scope verification and benchmarking of MILDOS-AREA by comparing spreadsheet calculation results with MILD OS-AREA-generated reports. The differences between the simple spreadsheet calculat ions and the MILDOS-AREA-generated reports were less than 5%, and in most cases the re sults were within 3%. The MILDOS-AREA air dispersion component was also compared with tha t of the RESRAD-OFFSITE code. The major differences between the two codes that were i dentified by ANL are presented below:

1 ANL/ES-161 actually compared MILDOS-AREA to AIRDOS -EPA. However, since CAP88 uses the same methodology for calculating Rn-222 air concentratio ns and working levels as AIRDOS-EPA, the results of the ANL/ES-161 comparison are valid for CAP88.WA 1-04, Task 3 11 SC&A – August 31, 2010

● Dose Outputs: Population doses and organ doses are not included in the

RESRAD-OFFSITE code.

● Different Default Values:

- The codes use different default dose conversion fac tors and consumption

rates.

- MILDOS-AREA assumes U-234 is in equilibrium with U- 238.

● Differences in Release, Dispersion, and Deposition Models:

- In RESRAD-OFFSITE, both dry deposition and wet depo sition are considered, whereas only dry deposition is consider ed in MILDOS-AREA.

- RESRAD-OFFSITE uses the average mass loading, depos ition velocity, average concentration, and source area to calculate the source term (release rate), whereas MILDOS-AREA uses windblown particle emission to calculate

the source term.

- The RESRAD-OFFSITE code does not include resuspensi on from ground surface deposition in air concentration calculation s.

- In RESRAD-OFFSITE, accumulation in offsite surface soil includes accumulation due both to irrigation with contaminat ed water and to deposition of contaminated dust, whereas only deposition of co ntaminated dust is

included in MILDOS-AREA.

- In RESRAD-OFFSITE, the soil concentration is affect ed by mixing in the surface layer, erosion, and leaching, whereas in MI LDOS-AREA, it is affected by the constant deposition and environment al loss.

- RESRAD-OFFSITE calculates the average air and soil concentrations from deposition for different selected areas, whereas MI LDOS-AREA calculates air concentration and ground deposition at a specified receptor location (no area associated).

● Differences in Exposure Pathways:

- The RESRAD-OFFSITE code does not include air submer sion pathway dose.

- External pathway dose in MILDOS-AREA is calculated by assuming infinite surface source, whereas RESRAD-OFFSITE calculates i t by assuming a finite

volume source with uniform concentration within the mixing layer.

- In calculating radionuclide concentration in the ed ible part of the plant, RESRAD-OFFSITE includes root uptake from contaminat ed soil, foliar uptake from overhead irrigation, and foliar uptake of dust; MILDOS-AREA does not include uptake from irrigation.

- There are five categories of plants in MILDOS-AREA: edible above-ground vegetables, potatoes, other edible below-ground veg etables, pasture grass, andWA 1-04, Task 3 12 SC&A – August 31, 2010 hay. The edible above-ground vegetables, potatoes, and below-ground vegetables are for human consumption, and pasture g rass and hay are for animal consumption. There are four categories of p lants in RESRADOFFSITE: fruit, grain, nonleafy vegetables; leafy vegetables; pasture and silage; and hay. The fruit, grain, nonleafy vegetab les and leafy vegetables are for human consumption, and pasture, silage and hay are for animal consumption.

- In RESRAD-OFFSITE, it is assumed that ingestion of contaminated plants, soil, and water all contribute to meat and milk con tamination. In MILDOSAREA, contaminated soil and water ingestion is not included.

2.6 MEPAS with FRAMES

The Mu1timedia Environmental Pollutant Assessment S ystem (MEPAS) is an integrated software implementation of physics-based fate and t ransport models for health and

environmental risk assessments of both radioactive and hazardous pollutants. MEPAS is a “multimedia” model in that pollutant transport is m odeled within, through, and between multiple media (air, soil, groundwater, and surface water). The estimated concentrations in the various media are used to compute exposures and impacts to the environment, to maximum individuals, and to populations. Of most import to this Work As signment, the MEPAS atmospheric component for the air media includes models for emi ssion from a source to the air, initial plume rise and dispersion, airborne pollutant transport a nd dispersion, and deposition to soils and crops.

MEPAS, developed by PNL, is a suite of integrated i mpact assessment software comprising physics-based fate and environmental transport mode ls of air, soil, and water media. MEPAS

simulates the release of contaminants from a source ; transport through the air, groundwater, surface water, and/or overland pathways; and transf er through food chains and exposure pathways to the exposed individual or population. For human health impacts, risks are computed for carcinogens and hazard quotients for noncarcino gens.

In DOE/ORO-2033, MEPAS was benchmarked against RESR AD-OFFSITE. Because CAP88 is linked to RESRAD to perform atmospheric dispersion calculations, DOE/ORO-2033 was, in effect, a benchmarking of CAP88 against MEPAS. The DOE/ORO-2033 results are summarized

above in Section 2.2.

The most current version of MEPAS operates within F RAMES. FRAMES allows the addition of other computer modules to MEPAS. Additional inf ormation on FRAMES is provided in

Section 2.3.1.

2.7 AERMOD

The American Meteorological Society/Environmental P rotection Agency Regulatory Model Improvement Committee (AERMIC) was formed to introd uce state-of-the-art modeling concepts into the EPA’s air quality models. Through AERMIC, a modeling system, AERMOD, was developed as a state-of-the-practice Gaussian plume dispersion model whose formulation is based on planetary boundary layer principles. The AERMOD model utilizes a probabilityWA 1-04, Task 3 13 SC&A – August 31, 2010

density function and the superposition of several G aussian plumes to characterize the distinctly non-Gaussian nature of the vertical pollutant distr ibution for elevated plumes during convective conditions; otherwise the distribution is Gaussian. Also, nighttime urban boundary layers (and plumes within them) have the turbulence enhanced by AERMOD to simulate the influence of the urban heat island. The AERMOD model is applicable to rural and urban areas, flat and complex terrain, surface and elevated releases, and multipl e sources (including point, area and volume sources).

The development of AERMOD began in 1991 and underwe nt seven steps: initial model formulation, developmental evaluation, internal pee r review/beta testing, revised model formulation, performance evaluation and sensitivity testing, external peer review, and submission to the EPA for consideration as a regula tory model. On November 9, 2005, EPA issued the final rule to replace the widely used In dustrial Source Complex (ISC) air dispersion model with the state-of-practice air dispersion mod el AERMOD in many air quality impact

assessments.

Because AERMOD only calculates atmospheric dispersi on and deposition, but not dose to individual and the population through the exposure pathways, it would be necessary to link AERMOD to either an existing or custom designed and developed program in order to evaluate dose and risk. Although it may be a worthwhile eff ort to upgrade the atmospheric dispersion capabilities of a dose evaluation program (such as CAP88) to include the AERMOD dispersion models, it is beyond the scope of this Work Assignm ent, and AERMOD will not be evaluated

further.

2.8 GASPAR-II

The GASPAR code was written in 1977 by Oak Ridge Na tional Laboratory for the NRC.

GASPAR is an air release dose code that models the release of noble gases in a semi-infinite plume, radioiodine and particulate emissions using the release model described in NRC Regulatory Guide 1.109 (NRC 1977). The code was de veloped mainly to analyze effluent releases from nuclear power operations. GASPAR con siders such pathways as inhalation, plume-immersion, ground-shine, and ingestion of var ious contaminated media (meat, milk, vegetation, etc.). Dose calculations can be applie d to a defined population or an individual who are evaluated for four age groups: infants (0-1 ye ars), children (1-11 years), teens (12-18 years), and adults (over 18 years). Each calculation consi ders seven organs (bone, G.I. tract, kidney, liver, lung, skin, and thyroid) as well as the whol e body dose.

In 1987, GASPAR-II was developed by PNL, however, w hile changes were made to the values of some parameters and dose factors used in the cod e, no changes were made to the mathematical models used by GASPAR.

GASPAR was eliminated from further consideration in this Work Assignment for the following

reasons:

• Dose factors – GASPAR-II utilizes the inhalation an d ingestion dose factors from ICRP Publication 2, as modified slightly in later ICRP d ocuments. Since ICRP Publication 2WA 1-04, Task 3 14 SC&A – August 31, 2010

was published in 1959, the ICRP has issued two majo r updates of its dosimetric guidance. The details of these ICRP updates have been provide d in SC&A 2009. Thus, the dosimetry used by GASPAR-II is out-of-date and cann ot be readily updated.

• Atmospheric dispersion – GASPAR-II does not calcula te atmospheric dispersion, therefore it would be necessary to utilize a separa te program (such as XOQDOQ) to process the raw meteorological data and generate at mospheric dispersion and deposition factors for input into GASPAR-II.

• Risk factors – GASPAR-II only calculates radiologic al dose, and does not calculate risk. Although it is possible to convert the doses report ed by GASPAR-II into risk by designing and using a post-processor, it is believe d that such an approach would not be practicable for various reasons, including the fact that the GASPAR-II doses are based on

ICRP Publication 2.

2.9 GENII-NESHAPS

GENII-NESHAPS is a modified version of the more gen eral GENII code which was designed to help site managers plan and improve compliance with 40 CFR 61, Subparts H and I. The code implements the same methods as the original GENII c ode, except it hardwires certain parameters so that they cannot be changed by the user. This w as done so that the code would automatically incorporate certain elements necessary to the NESHA PS regulation.

The following statement is currently being displaye d on the EPA website ( http://www.epa.gov/ rpdweb00/neshaps/models.html ):

EPA does not presently support GENII-NESHAPs, and t here is no intention to do so.

Because of this and the fact that GENII is being ev aluated for use, GENII-NESHAPS was

eliminated from further consideration in this Work Assignment.WA 1-04, Task 3 15 SC&A – August 31, 2010

3.0 DETAILED MODEL EVALUATIONS

3.1 Evaluation Criteria

The evaluation criteria used were:

● Exposure Pathways Modeled (2) : Are all of the exposure pathways that are essent ial to this analysis included in the code? Additionally, does the code allow for exposures to different age groups (i.e., adults, teens, children , infants) and/or sexes to be calculated?

● Population Based Dose/Risk Capability (2) : Does the code allow for the calculation of a population dose/risk based on a site-specific uni que population distribution or does the code only allow the calculation of dose/risk based on a single defined receptor location?

● Dose Factors Used (1.75) : Does the code utilize dose conversion factors ba sed on the most recent International Commission on Radiologica l Protection (ICRP)

recommendations?

● Risk Factors Used (1.75) : Does the code utilize the most recent risk facto rs?

● Processing of Meteorological Data (1.5) : Can the code process “raw” meteorological data, or does the meteorological data need to be pr e-processed prior to being entered into the code? For example, does the code accept “raw” meteorological tower data (e.g., from http://www.epa.gov/scram001/surfacemetdata.htm), or does it accept joint frequency data, or does it only accept dispersion and deposit ion factors? If a code does not include the capability to process “raw” meteorological data , than a separate code (e.g., STAR from http://www.epa.gov/scram001/metobsdata_procacc progs.htm) would need to be run to generate the input necessary for the risk assess ment model.

● Source Term Calculation (1.5) : Can the code calculate radon releases, or must t he releases be pre-calculated and entered into the cod e? If a code does not include the capability to calculate the radon release, than an additional calculation would be needed

to estimate the source term so that it can be enter ed into the risk assessment model. Alternatively, a code that contains an internal sou rce term calculation would be difficult to modify should the source term model change.

● Verification and Validation (1.25) : Is there a readily available V&V package that supports the code? Is the V&V package complete? H as there been independent (i.e., by someone other than the code’s developer) V&V perfor med?

● Ease of Use/User Friendly (1.25) : Is the code provided with a user interface that is intuitive and easy to understand and use? Alternat ively, does the code require the user to manipulate structured input data files? Additional ly, does the code have features not required for this analysis, but that might complica te its use?

● Documentation (1) : Is the code well documented? Are there User’s M anuals readily available? In addition to providing instructions a s to how to use the code, are the mathematical models used by the code well documente d? It is expected that all of the codes selected for evaluation would have high score s for this criteria.WA 1-04, Task 3 16 SC&A – August 31, 2010

● Input Parameter Sensitivity Analysis (1) : Does the code have the capability to perform sensitivity analyses on the input data, or must par ameter sensitivity be determined by multiple runs, each run varying a single parameter? EPA 1989, Section 7 describes uncertainty analyses that were performed. Although this Work Assignment does not specify them, EPA may want to perform similar uncer tainty analyses for this revision in

the future.

● Probabilistic Analysis Capability (1) : Is there a probabilistic analysis version of the code available? Although the calculations being pe rformed for WA 1-04 are being done deterministically, at some point the EPA may desire to perform a probabilistic analysis,

and it would be desirable to use the same code for both analyses.

● SC&A Familiarity (tie breaker) : If two or more models have identical (or nearly identical [i.e., within 10%]) scores based on the a bove criteria, then the SC&A

recommendation will be based on how familiar SC&A i s with the operation of each code.

The above list of evaluation criteria is preliminar y, and SC&A will work with the Work Assignment Manager (WAM) to finalize the code evalu ation criteria. As can be seen from the above list, some criteria are of greater importance that other criteria. To account for this, each criterion will be given a weighting factor ranging from 1 to 2; preliminary weighting factors are shown in parenthesis on the above list of evaluatio n criteria. SC&A will work with the WAM to develop the final weighting factors for each criter ion. The final score of the evaluation will be the sum of each criterion’s score times its weighti ng factor.

Table 1. Evaluation Criteria

Evaluation Criteria Weight

Factor Exposure Pathways Modeled 2 Population Dose/Risk Capability 2

Dose Factors Used 1.75

Risk Factors Used 1.75 Meteorological Data Processing 1.5

Source Term Calculations 1.5

Verification and Validation 1.25 Ease of Use/User Friendly 1.25

Documentation 1 Sensitivity Analysis Capability 1 Probabilistic Analysis Capability 1 SC&A Familiarity N/A

3.2 CAP88

3.2.1 Exposure Pathways Modeled (2)

Criteria : Are all of the exposure pathways that are essent ial to this analysis included in the code? Additionally, does the code allow for exposu res to different age groups (i.e., adults, teens, children, infants) and/or sexes to be calculated?WA 1-04, Task 3 17 SC&A – August 31, 2010

Evaluation : CAP88 calculated dose and risk from exposure pat hways including ingestion, inhalation, ground-level immersion (external), and ground-surface irradiation (external).

In cases considering Rn-222 decay products, CAP88 c alculates the working levels associated with the contaminants and evaluates the risk, but n ot dose, from the working level calculations.

Code documentation states that current version ‘con tains (not implemented) data for – age dependent dose factors’. It does not appear that t his is a selectable option, nor does it appear to report age-specific analyses in the output files. No mention of gender-specific analyses in the

associated documentation. Previous versions of the code implemented a ‘genetic effects’

calculation which has been removed.

Score : 5 Weighted Score: 10

3.2.2 Dose Factors Used (1.75)

Criteria : Does the code utilize dose conversion factors ba sed on the most recent International Commission on Radiological Protection (ICRP) recomm endations?

Evaluation : “CAP-88 uses a database of dose and risk factors provided in Federal Guidance Report 13. Dose and risk conversion factors includ e the effective dose equivalent calculated according to the methods of ICRP Publication Number 72 (ICRP 72).” – User Guide 12/9/07.

ICRP-72 are the most recent dose conversion factors used in the codes under evaluation.

Score : 5 Weighted Score: 8.75

3.2.3 Risk Factors Used (1.75)

Criteria : Does the code utilize the most recent risk facto rs?

Evaluation : “CAP-88 uses a database of dose and risk factors provided in Federal Guidance Report 13. Dose and risk conversion factors includ e the effective dose equivalent calculated according to the methods of ICRP Publication Number 72 (ICRP 72).” – User Guide 12/9/07

Score : 5 Weighted Score: 8.75

3.2.4 Population Based Dose/Risk Capability (2):

Criteria : Does the code allow for the calculation of a pop ulation dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk based on a single defined receptor location?WA 1-04, Task 3 18 SC&A – August 31, 2010

Evaluation : CAP88 allows for the calculation of dose/risk ba sed on both a maximally exposed individual (user defined) or additionally to load p opulation data in the form of a ‘.POP’ file. The CAP88 software package contains 28 preloaded popula tion files.

Score : 5 Weighted Score: 10

3.2.5 Meteorological Data Processing (1.5)

Criteria : Can the code process “raw” meteorological data, or does the meteorological data need to be pre-processed prior to being entered into the code? For example, does the code accept “raw” meteorological tower data, or does it accept joint frequency data, or does it only accept dispersion and deposition factors?

Evaluation : ‘Wind Files’ (as created by the National Weather Service) are required to run CAP88. Site-specific meteorological data can be pr ocessed using an associated ‘Stability Array

Distribution’ module to convert the on-site data to the correctly formatted ‘Wind File’. The

module GETWIND allows for the conversion of STAR fo rmatted meteorological data to the

CAP88 formatted ‘wind file’.

Meteorological data files from over 350 sites withi n the U.S. are provided as part of the CAP88 code package.

Score : 5 Weighted Score: 7.5

3.2.6 Source Term Calculation (1.5)

Criteria : Can the code calculate radon releases, or must t he releases be pre-calculated and

entered into the code?

Evaluation : Radionuclide releases are entered manually in CA P88 in the form of Curie/yr.

Score : 2 Weighted Score: 3

3.2.7 Verification and Validation (1.25)

Criteria : Is there a readily available V&V package that su pports the code? Is the V&V package complete? Has there been independent (i.e., by som eone other than the code’s developer) V&V performed?

Evaluation : Main QA Documents:

Maheras, S.J.; Ritter, P.D.; Leonard, P.R.; and Moo re, R. Benchmarking of the CAP-88 and GENII Computer Codes Using 1990 and 1991 Monitored Atmospheric Releases from the Idaho National Engineering Laboratory , Health Physics 67:509-517; November 1994.WA 1-04, Task 3 19 SC&A – August 31, 2010

Fields, D.E.; Miller, C.W.; Cotter, S.J. Validation of the AIRDOS-EPA Computer Codes by Simulating Intermediate Range Transport of Kr-85 fr om the Savannah River Plant . Atmos. Environ. 18:2029-2036; 1984.

Score : 5 Weighted Score: 6.25

3.2.8 Ease of Use/User Friendly (1.25)

Criteria : Is the code provided with a user interface that is intuitive and easy to understand and use? Alternatively, does the code require the user to manipulate structured input data files? Additionally, does the code have features not requi red for this analysis, but that might complicate

its use?

Evaluation : Code contains very intuitive menus which prompt the user in a linear fashion to enter all pertinent model data. Of the five main c odes analyzed in detail, CAP88 is the easiest to implement and most user friendly.

Score : 5 Weighted Score: 6.25

3.2.9 Documentation (1)

Criteria : Is the code well documented? Are there User’s M anuals readily available? In addition to providing instructions as to how to use the code, are the mathematical models used by

the code well documented?

Evaluation : The mathematical models and equations used by th e code are presented in Chapter 12 of the user’s guide.

“Mathematical Models in CAP88-PC” (Parks, DOE, 1997 ) provides additional documentation beyond the User’s Manual.

Score : 5 Weighted Score: 5

3.2.10 Sensitivity Analysis Capability (1)

Criteria : Does the code have the capability to perform sen sitivity analyses on the input data, or must parameter sensitivity be determined by multipl e runs, each run varying a single parameter?

Evaluation : Sensitivity analyses can only be carried out usi ng individual runs.

Score : 0 Weighted Score: 0

3.2.11 Probabilistic Analysis Capability (1)

Criteria : Is there a probabilistic analysis version of the code available?WA 1-04, Task 3 20 SC&A – August 31, 2010

Evaluation : Probabilistic analysis is not available for this code.

Score : 0 Weighted Score: 0

3.2.12 SC&A Familiarity (N/A)

Criteria : To be used as a tiebreaker when the top two code s have a final score within 10% of

each other.

Evaluation : SC&A has very good overall familiarity with the CAP88 code, as SC&A helped assist EPA in the development of the mainframe vers ion of the code, as well as assisted in writing the User’s Manual. Since that time, SC&A h as continued to use CAP88 in our consulting work for various clients.

3.3 GENII with FRAMES

3.3.1 Exposure Pathways Modeled (2)

Criteria : Are all of the exposure pathways that are essent ial to this analysis included in the code? Additionally, does the code allow for exposu res to different age groups (i.e., adults, teens, children, infants) and/or sexes to be calculated?

Evaluation : Exposure pathways include: external (air immers ion, ground-shine, recreational swimming/boating/shoreline exposure), ingestion (fo od crops, animal products, aquatic food, inadvertent soil, drinking water), and inhalation ( air, resuspended soil, inhalation of waterborne contaminants).

Radon is considered a special radionuclide model fo r GENII along with tritium and carbon-14.

Score : 5 Weighted Score: 10

3.3.2 Dose Factors Used (1.75)

Criteria : Does the code utilize dose conversion factors ba sed on the most recent International Commission on Radiological Protection (ICRP) recomm endations?

Evaluation : “The GENII computer code was developed for the E nvironmental Protection Agency (EPA) at Pacific Northwest National Laborato ry (PNNL) to incorporate the internal dosimetry models recommended by the International C ommission on Radiological Protection (ICRP) and radiological risk estimating procedures of Federal Guidance Report 13 into updated versions of existing environmental pathway analysis models.”– GENII Users’ Guide, October

2004

ICRP documents are noted as publications 56-72.

Score : 4 Weighted Score: 7WA 1-04, Task 3 21 SC&A – August 31, 2010

3.3.3 Risk Factors Used (1.75)

Criteria : Does the code utilize the most recent risk facto rs?

Evaluation : “The GENII computer code was developed for the E nvironmental Protection Agency (EPA) at Pacific Northwest National Laborato ry (PNNL) to incorporate the internal dosimetry models recommended by the International C ommission on Radiological Protection (ICRP) and radiological risk estimating procedures of Federal Guidance Report 13 into updated versions of existing environmental pathway analysis models.”– GENII Users’ Guide, October

2004

Score : 5 Weighted Score: 8.75

3.3.4 Population Based Dose/Risk Capability (2):

Criteria : Does the code allow for the calculation of a pop ulation dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk based on a single defined receptor location?

Evaluation : GENII within FRAMES can perform calculations for populations but must have population distributions that match the format of t he meteorological data and must be constructed in ASCII format by the user. GENII doe s not have any preloaded population files

available.

Score : 3 Weighted Score: 6

3.3.5 Meteorological Data Processing (1.5)

Criteria : Can the code process “raw” meteorological data, or does the meteorological data need to be pre-processed prior to being entered into the code? For example, does the code accept “raw” meteorological tower data, or does it accept joint frequency data, or does it only accept dispersion and deposition factors?

Evaluation : GENII uses its own specific format for meteorolo gical data, but contains modules to convert some different data types such as:

- two different types of JFD (Joint Frequency Data) d ata: EPA’s Industrial Source Complex model (ISC3 also known as STAR summary), an d the format used by the original GENII (1988).

- “Card Deck 144 format” (CD-144) and SAMSON data for mat: available from the National Climatic Data Center (NCDC).

Score : 5 Weighted Score: 7.5WA 1-04, Task 3 22 SC&A – August 31, 2010

3.3.6 Source Term Calculation (1.5)

Criteria : Can the code calculate radon releases, or must t he releases be pre-calculated and

entered into the code?

Evaluation : All radionuclide releases, whether acute or chro nic, must be entered into GENII by the user. GENII does not have any capability to ca lculate the airborne release of radon.

Score : 2 Weighted Score: 3

3.3.7 Verification and Validation (1.25)

Criteria : Is there a readily available V&V package that su pports the code? Is the V&V package complete? Has there been independent (i.e., by som eone other than the code’s developer) V&V performed?

Evaluation : “Both GENII versions were developed under QA pla ns based on the American National Standards Institute (ANSI) standard NQA-1 as implemented in the PNNL Quality Assurance Manual. All steps of the code developmen t have been documented and tested, and hand calculations have verified the code’s implemen tation of major transport and exposure pathways for a subset of the radionuclide library. A collection of hand calculations and other

verification activities is available... The code has been reviewed by the EPA Science Advisory Board and a separate EPA-sponsored, independent pee r review panel. The QA of both GENII Version 1.485 and Version 2 have been reviewed by t he US Department of Energy.” – GENII Users’ Guide, October 2004

Score : 5 Weighted Score: 6.25

3.3.8 Ease of Use/User Friendly (1.25)

Criteria : Is the code provided with a user interface that is intuitive and easy to understand and use? Alternatively, does the code require the user to manipulate structured input data files? Additionally, does the code have features not requi red for this analysis, but that might complicate

its use?

Evaluation : GENII Version 2 functions within FRAMES which al lows the code to run in conjunction with, and provide input to, other model ing codes (such as MEPAS). While this allows for more dynamic modeling efforts using GENI I with other codes, the strict use of GENII is not as straightforward because of the complexity of integrating the different codes and executing the FRAMES system itself.

Score : 1 Weighted Score: 1.25WA 1-04, Task 3 23 SC&A – August 31, 2010

3.3.9 Documentation (1)

Criteria : Is the code well documented? Are there User’s M anuals readily available? In addition to providing instructions as to how to use the code, are the mathematical models used by

the code well documented?

Evaluation : User manuals and input guidance reports are read ily available on the Internet from various reputable sources. Equations and methodolo gy underlying the code is well documented

in:

Napier, B.A.; Strenge, D.L.; Ramsdell Jr., J.V.; Es linger, P.W.; Fosmire, C. GENII Version 2 Software Design Document. Prepared for U.S. Enviro nmental Protection Agency. November

2004.

Score : 5 Weighted Score: 5

3.3.10 Sensitivity Analysis Capability (1)

Criteria : Does the code have the capability to perform sen sitivity analyses on the input data, or must parameter sensitivity be determined by multipl e runs, each run varying a single parameter?

Evaluation : GENII does include a ‘Sensitivity and Uncertaint y’ module as described in the following: “FRAMES is currently designed for deter ministic environmental and human health impact models. The Sensitivity/Uncertainty Multime dia Modeling Module (SUM3) software product was designed to allow statistical analysis using the existing deterministic models available in FRAMES. SUM3 randomly samples input v ariables and preserves the associated output values in an external file available to the user for evaluation.”

Score : 4 Weighted Score: 4

3.3.11 Probabilistic Analysis Capability (1)

Criteria : Is there a probabilistic analysis version of the code available?

Evaluation : The GENII Sensitivity and Analysis module allows the user to specify probabilistic distributions to various deterministic parameters; this feature appears to be used only for determining which parameters contribute the most to the uncertainty of the output, but not necessarily allow the user to run a probabilistic s imulation which produces a distribution of output values.

Score : 4 Weighted Score: 4

3.3.12 SC&A Familiarity (N/A)

Criteria : To be used as a tiebreaker when the top two code s have a final score within 10% of

each other.WA 1-04, Task 3 24 SC&A – August 31, 2010

Evaluation : SC&A has previously used GENII to support EPA’s evaluation of the technical and regulatory issues associated with the disposition o f scrap metal from nuclear facilities, as well as to support EPA in the development of radiological e xposure standards for the Yucca Mountain high-level waste disposal facility. However, altho ugh we have obtained and installed FRAMESbased GENII for this Work Assignment, to date, SC&A has not had the opportunity to use FRAMES-based GENII in any of our work.

3.4 RESRAD-OFFSITE

3.4.1 Exposure Pathways Modeled (2)

Criteria : Are all of the exposure pathways that are essent ial to this analysis included in the code? Additionally, does the code allow for exposu res to different age groups (i.e., adults, teens, children, infants) and/or sexes to be calculated?

Evaluation : RESRAD is designated to evaluate ground contamin ation with residual radioactivity, not the airborne release pathways, a lthough it does contain a radon model. It is important to note that RESRAD’s offsite air transpo rt model utilizes the CAP88 methodology.

Exposure pathways evaluated by RESRAD-OFFSITE inclu de external gamma, inhalation, ingestion (plant, meat, milk, aquatic, inadvertent soil, drinking water), and radon. Internal dose conversion factors for ICRP-72 include factors by a ge (infant, 1, 5, 10, 15, and adult). No gender-specific analysis is available.

Score : 5 Weighted Score: 10

3.4.2 Dose Factors Used (1.75)

Criteria : Does the code utilize dose conversion factors ba sed on the most recent International Commission on Radiological Protection (ICRP) recomm endations?

Evaluation : Selectable between FGR 11 and ICRP-72 for intern al exposures, FGR 12 and ICRP-60 for external exposures.

Score : 5 Weighted Score: 8.75

3.4.3 Risk Factors Used (1.75)

Criteria : Does the code utilize the most recent risk facto rs?

Evaluation : Risk factors are selectable between FGR 13 (morb idity/mortality) and Heast (2001) morbidity coefficients.

Score : 5 Weighted Score: 8.75WA 1-04, Task 3 25 SC&A – August 31, 2010

3.4.4 Population Based Dose/Risk Capability (2):

Criteria : Does the code allow for the calculation of a pop ulation dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk based on a single defined receptor location?

Evaluation : RESRAD can only calculate dose to an individual receptor as defined by the user. Population-based dose and risk calculations are not available with RESRAD- OFFSITE.

Score : 0 Weighted Score: 0

3.4.5 Meteorological Data Processing (1.5)

Criteria : Can the code process “raw” meteorological data, or does the meteorological data need to be pre-processed prior to being entered into the code? For example, does the code accept “raw” meteorological tower data, or does it accept joint frequency data, or does it only accept dispersion and deposition factors?

Evaluation : Joint frequency data can be input manually into the code or can also be read from a ‘STAR’ file. A single stability class/wind speed c an also be used in place of the joint frequency

data.

Meteorological data (in the STAR format) for 267 U. S. sites are provided with the code package.

Score : 5 Weighted Score: 7.5

3.4.6 Source Term Calculation (1.5)

Criteria : Can the code calculate radon releases, or must t he releases be pre-calculated and

entered into the code?

Evaluation : The code requires input of diffusion coefficient s (from soil/cover, floor of a building, etc.) and other properties of radon, such as an emanation coefficient which will define

the radon release value.

Score : 4 Weighted Score: 6

3.4.7 Verification and Validation (1.25)

Criteria : Is there a readily available V&V package that su pports the code? Is the V&V package complete? Has there been independent (i.e., by som eone other than the code’s developer) V&V performed?

Evaluation : The V&V package is contained in the document:WA 1-04, Task 3 26 SC&A – August 31, 2010

Yu, C.; Gnanapragasam, E.; Cheng, J.J.; Biwer, B. Benchmarking of RESRAD-OFFSITE: Transition from RESRAD (onsite) to RESRAD-OFFSITE a nd Comparison of the RESRADOFFSITE Predictions with Peer Codes. Environmental Science Division of Argonne National Laboratory.

The document compares the code against CAP88 and IS CLT3 for atmospheric transport calculations and also against the base RESRAD code for onsite calculations, which itself was benchmarked against GENII-S, DECOM, PRESTO-EPA-CPG, and the NUREG/CR-5512 methodology.

Score : 5 Weighted Score: 6.25

3.4.8 Ease of Use/User Friendly (1.25)

Criteria : Is the code provided with a user interface that is intuitive and easy to understand and use? Alternatively, does the code require the user to manipulate structured input data files? Additionally, does the code have features not requi red for this analysis, but that might complicate

its use?

Evaluation : The code brings the user in a linear fashion thr ough each of the input screens and provides a default value which will fit most situat ions. If the user tries to input a value that is outside the theoretical range for a given parameter , the code notifies the user and blocks them from entering the given value.

Score : 4 Weighted Score: 2.5

3.4.9 Documentation (1)

Criteria : Is the code well documented? Are there User’s M anuals readily available? In addition to providing instructions as to how to use the code, are the mathematical models used by

the code well documented?

Evaluation : The main User Manual is available on the main co de’s website which includes both a User’s Guide (Appendix A of the document) and the methods and equations used by the code (main body of the User Manual).

Score : 5 Weighted Score: 5

3.4.10 Sensitivity Analysis Capability (1)

Criteria : Does the code have the capability to perform sen sitivity analyses on the input data, or must parameter sensitivity be determined by multipl e runs, each run varying a single parameter?WA 1-04, Task 3 27 SC&A – August 31, 2010

Evaluation : RESRAD-OFFSITE contains a sensitivity module tha t (unlike the basic RESRAD code) does not limit the number of parameters subje cted to sensitivity in any given run. The sensitivity module can be run either by dividing/mu ltiplying an input value by a discreet number.

Score : 5 Weighted Score: 5

3.4.11 Probabilistic Analysis Capability (1)

Criteria : Is there a probabilistic analysis version of the code available?

Evaluation : RESRAD-OFFSITE contains a probabilistic analysis feature that allows the user to specify a given distribution type (from 35 differen t choices: normal, lognormal, truncated lognormal, etc.) and specify the characteristics of the distribution. RESRAD-OFFSITE provides a default probabilistic distribution for each param eter which is documented in the RESRADOFFSITE user guide.

Score : 4 Weighted Score: 4

3.4.12 SC&A Familiarity (N/A)

Criteria : To be used as a tiebreaker when the top two code s have a final score within 10% of

each other.

Evaluation : SC&A is very familiar with RESRAD and RESRAD-OFF SITE. We have run the code on numerous occasions, and in addition have us ed the RESRAD methodology as provided in the User’s Manual in our own analyses (e.g., the development of NUREG-1640).

3.5 MILDOS-AREA

3.5.1 Exposure Pathways Modeled (2)

Criteria : Are all of the exposure pathways that are essent ial to this analysis included in the code? Additionally, does the code allow for exposu res to different age groups (i.e., adults, teens, children, infants) and/or sexes to be calculated?

Evaluation : MILDOS-AREA considers inhalation, external (grou ndshine and cloud immersion), and ingestion (vegetables, meat and mil k).

Score : 5 Weighted Score: 10

3.5.2 Population Based Dose/Risk Capability (2):

Criteria : Does the code allow for the calculation of a pop ulation dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk based on a single defined receptor location?WA 1-04, Task 3 28 SC&A – August 31, 2010

Evaluation : MILDOS-AREA allows the user to load in a ‘.pop’ file similar to CAP88. MILDOS does not have any preloaded population distr ibutions. Users can also create their own population files with properly formatted ASCII text documents.

Score : 4 Weighted Score: 8

3.5.3 Dose Factors Used (1.75)

Criteria : Does the code utilize dose conversion factors ba sed on the most recent International Commission on Radiological Protection (ICRP) recomm endations?

Evaluation : Dose conversion factors are based on ICRP 26 (19 78) recommendations.

Score : 2 Weighted Score: 3.5

3.5.4 Risk Factors Used (1.75)

Criteria : Does the code utilize the most recent risk facto rs?

Evaluation : MILDOS-AREA appears to only calculate dose and n ot incorporate risk calculations into its output.

Score : 0 Weighted Score: 0

3.5.5 Meteorological Data Processing (1.5)

Criteria : Can the code process “raw” meteorological data, or does the meteorological data need to be pre-processed prior to being entered into the code? For example, does the code accept “raw” meteorological tower data, or does it accept joint frequency data, or does it only accept dispersion and deposition factors?

Evaluation : Joint frequency data can be input manually into the code or can also be read from a ‘STAR’ file. Although meteorological data is not p rovided with MILDOS-AREA, the CAP88 supplied meteorological data is in the STAR format and can be used with MILDOS-AREA. Alternatively, the RESRAD-OFFSITE supplied joint fr equency data can be converted to the

STAR format and used with MILDOS-AREA.

Score : 4 Weighted Score: 6

3.5.6 Source Term Calculation (1.5)

Criteria : Can the code calculate radon releases, or must t he releases be pre-calculated and

entered into the code?WA 1-04, Task 3 29 SC&A – August 31, 2010

Evaluation : MILDOS-AREA is limited to only analyzing the U-2 38 decay series, specifically, U-238, Th-230, Ra-226, Pb-210, and Rn-222. MILDOS- AREA gives the user the option of entering the particulate release rates or of having the code calculate them.

Score : 2 Weighted Score: 3

3.5.7 Verification and Validation (1.25)

Criteria : Is there a readily available V&V package that su pports the code? Is the V&V package complete? Has there been independent (i.e., by som eone other than the code’s developer) V&V performed?

Evaluation : The document: ‘Verification and Benchmarking of the MILDOS-Area Code’ is

available on the MILDOS-AREA website and contains i nternal quality assurance studies, benchmarking of the air release model against RESRA D-OFFSITE, and also verifications of modeled results against ‘spreadsheet calculations’ based on NUREG 1569 for a select ISL facility.

Score : 5 Weighted Score: 6.25

3.5.8 Ease of Use/User Friendly (1.25)

Criteria : Is the code provided with a user interface that is intuitive and easy to understand and use? Alternatively, does the code require the user to manipulate structured input data files? Additionally, does the code have features not requi red for this analysis, but that might complicate

its use?

Evaluation : MILDOS-AREA is one of the most user-friendly of the main codes under assessment with simplistic data inputs that lead th e user through each of the menus before running the code.

Score : 5 Weighted Score: 6.25

3.5.9 Documentation (1)

Criteria : Is the code well documented? Are there User’s M anuals readily available? In addition to providing instructions as to how to use the code, are the mathematical models used by

the code well documented?

Evaluation : User’s Guide is readily available for the MILDOS -AREA code along with a User’s Manual which describes the underlying methods and e quations used. Both can be found on the

main website for MILDOS-AREA.

Score : 5 Weighted Score: 5WA 1-04, Task 3 30 SC&A – August 31, 2010

3.5.10 Sensitivity Analysis Capability (1.5)

Criteria : Does the code have the capability to perform sen sitivity analyses on the input data, or must parameter sensitivity be determined by multipl e runs, each run varying a single parameter?

Evaluation : MILDOS-AREA does not have a sensitivity feature.

Score : 0 Weighted Score: 0

3.5.11 Probabilistic Analysis Capability (1)

Criteria : Is there a probabilistic analysis version of the code available?

Evaluation : MILDOS-AREA does not have a probabilistic analys is feature.

Score : 0 Weighted Score: 0

3.5.12 SC&A Familiarity (N/A)

Criteria : To be used as a tiebreaker when the top two codes have a final score within 10% of

each other.

Evaluation : Although we have obtained and installed MILDOS-A REA for this Work Assignment, to date, SC&A has not had the opportuni ty to use MILDOS-AREA in any of our

work.

3.6 MEPAS with FRAMES

3.6.1 Exposure Pathways Modeled (2)

Criteria : Are all of the exposure pathways that are essent ial to this analysis included in the code? Additionally, does the code allow for exposu res to different age groups (i.e., adults, teens, children, infants) and/or sexes to be calculated?

Evaluation : MEPAS models inhalation, ingestion, external exp osure and dermal contact.

Score : 5 Weighted Score: 10

3.6.2 Population Based Dose/Risk Capability (2):

Criteria : Does the code allow for the calculation of a pop ulation dose/risk based on a sitespecific unique population distribution or does the code only allow the calculation of dose/risk based on a single defined receptor location?

Evaluation : Similar to GENII, MEPAS within FRAMES can perfor m calculations for populations but must have population distributions that match the format of the meteorologicalWA 1-04, Task 3 31 SC&A – August 31, 2010

data and must be constructed in ASCII format by the user. Also like GENII, there do not appear to be any preloaded population files present with t he software.

Score : 3 Weighted Score: 6

3.6.3 Dose Factors Used (1.75)

Criteria : Does the code utilize dose conversion factors ba sed on the most recent International Commission on Radiological Protection (ICRP) recomm endations?

Evaluation : Per the MEPAS website: “Health impacts from expo sure to radiation are estimated using health effects conversion factors or USEPA sl ope factors... values are based on recommendation given in the BEIR V report (NAS 1990 ) and International Commission on Radiological Protection (ICRP) Publication 60 (ICRP 1990).”

Score : 4 Weighted Score: 7

3.6.4 Risk Factors Used (1.75)

Criteria : Does the code utilize the most recent risk facto rs?

Evaluation : Per the MEPAS website: “Two methods are availab le to estimate the risk of cancer

fatalities: use of health- effects conversion fact ors and use of USEPA slope factors.” Slope factors are based on USEPA (U.S. Environmental Prot ection Agency). 1994. Health Effects Assessment Summary Tables FY 1994 - Supplement Numb er 2. EPA/540/R-94/114. Office of Emergency and Remedial Response, Washington, D.C.

Score : 5 Weighted Score: 8.75

3.6.5 Meteorological Data Processing (1.5)

Criteria : Can the code process “raw” meteorological data, or does the meteorological data need to be pre-processed prior to being entered into the code? For example, does the code accept “raw” meteorological tower data, or does it accept joint frequency data, or does it only accept dispersion and deposition factors?

Evaluation : MEPAS accepts joint frequency data as a user inp ut. It has not been established

whether modules exist in the MEPAS suite of tools t o convert and analyze meteorological data in other formats, as GENII contains.

Score : 4 Weighted Score: 6

3.6.6 Source Term Calculation (1.5)

Criteria : Can the code calculate radon releases, or must th e releases be pre-calculated and

entered into the code?WA 1-04, Task 3 32 SC&A – August 31, 2010

Evaluation : Contaminant releases are provided by the AFF fil e; it is not clear from associated documentation whether releases are manually input b y the user. Inspection of example problems provided with code package, indicate that the relea se data are likely a user input.

Score : 2 Weighted Score: 3

3.6.7 Verification and Validation (1.25)

Criteria : Is there a readily available V&V package that su pports the code? Is the V&V package complete? Has there been independent (i.e., by som eone other than the code’s developer) V&V performed?

Evaluation : No V&V package has been located with the MEPAS d ocumentation available on the main website, though certain documents that app ear to benchmark the code are listed as a

reference on the main site.

Score : 4 Weighted Score: 6

3.6.8 Ease of Use/User Friendly (1.25)

Criteria : Is the code provided with a user interface that is intuitive and easy to understand and use? Alternatively, does the code require the user to manipulate structured input data files? Additionally, does the code have features not requi red for this analysis, but that might complicate

its use?

Evaluation : MEPAS functions within FRAMES which allows the c ode to run in conjunction with, and provide input to, other modeling codes (s uch as GENII). While this allows for more dynamic modeling efforts, the strict use of MEPAS i s not as straightforward because of the complexity of integrating the different codes and e xecuting the FRAMES system itself.

Score : 1 Weighted Score: 1.25

3.6.9 Documentation (1)

Criteria : Is the code well documented? Are there User’s M anuals readily available? In addition to providing instructions as to how to use the code, are the mathematical models used by

the code well documented?

Evaluation : User manuals are presented in html form via the MEPAS website; no current hardcopy versions (PDF) have been located. Website contains methodology and equations used by the code. A user guide presenting data input pr ocesses or example problems was not located.

Score : 3 Weighted Score: 3WA 1-04, Task 3 33 SC&A – August 31, 2010

3.6.10 Sensitivity Analysis Capability (1)

Criteria : Does the code have the capability to perform sen sitivity analyses on the input data, or must parameter sensitivity be determined by multipl e runs, each run varying a single parameter?

Evaluation : MEPAS does include a ‘Sensitivity and Uncertaint y’ module as described in the following: “FRAMES is currently designed for determ inistic environmental and human health impact models. The Sensitivity/Uncertainty Multime dia Modeling Module (SUM3) software product was designed to allow statistical analysis using the existing deterministic models available in FRAMES. SUM3 randomly samples input v ariables and preserves the associated output values in an external file available to the user for evaluation.”

Score : 4 Weighted Score: 4

3.6.11 Probabilistic Analysis Capability (1)

Criteria : Is there a probabilistic analysis version of the code available?

Evaluation : From the main MEPAS website: “MEPAS is implemen ted on a desktop computer with a user-friendly interface that allows the user to define the problem, input the required data, and execute the appropriate models for both determi nistic and probabilistic analyses.”

Score : 4 Weighted Score: 4

3.6.12 SC&A Familiarity (N/A)

Criteria : To be used as a tiebreaker when the top two code s have a final score within 10% of

each other.

Evaluation : Although we have obtained and installed FRAMES-b ased MEPAS for this Work Assignment, to date, SC&A has not had the opportuni ty to use FRAMES-based MEPAS in any

of our work.WA 1-04, Task 3 34 SC&A – August 31, 2010

4.0 RESULTS AND RECOMMENDATIONS

Table 2 summarizes the results of the code evaluati on as presented in Section 3. As shown, RESRAD-OFFSITE was the highest scoring of the five codes, narrowly edging out CAP88. However, it is recommended that CAP88, and not RESR AD-OFFSITE, be used to perform the dose and risk calculations required for this Work A ssignment. The reasons for this

recommendation include:

• RESRAD-OFFSITE does not include the ability to perf orm population dose and risk estimates, which means that the RESRAD-OFFSITE resu lts would need to be supplemented with population dose and risk estimate s from another source. CAP88, on the other hand, is specifically designed to assess radiological emissions to the public.

• The major area where CAP88 is lacking is sensitivit y and probability analyses. For this Work Assignment, it is not anticipated that sensiti vity or probability analysis will play a major role.

• RESRAD-OFFSITE incorporates CAP88 air dispersion mo deling, which means that there are no significant technical differences betw een the two codes for the purpose of this Work Assignment.

• CAP88 was developed as a predecessor to AIRDOS, whi ch was the original code used in the evaluation of mill tailing impoundments during the development of NESHAPs for

radon emissions in 1989.

GENII also finished high in the detailed evaluation ; however, the main concern with GENII is that it currently is only available within FRAMES. As stated in Section 2.3.1, it was found that the process necessary to setup and run GENII within FRAMES was complicated relative to setting up and running pre-FRAMES GENII, and the pr esent FRAMES GENII combination does not provide any technical advantage over the pre-FR AMES GENII. There are similar concerns regarding using MEPAS within FRAMES. The concern w ith FRAMES resulted in both GENII and MEPAS receiving low Ease of Use/User Friendly s cores, which resulted in neither of them being selected for use.

MILDOS-AREA received the lowest ranking in the deta iled evaluation, primarily due to its inability to perform risk calculations, which is a major component of this Work Assignment. Although it does not impact this Work Assignment, M ILDOS-AREA is limited to evaluating only the isotopes of the U-238 decay series, which means that another code would be required if other nuclear fuel cycle facilities were to be eval uated, such as was done in the 1989 analysis.WA 1-04, Task 3 35 SC&A – August 31, 2010

Table 2. Summary of Suitability Review for Five Co des Under Evaluation

Evaluation

Criteria CAP88 GENII via

FRAMES RESRADOFFSITE MILDOSAREA MEPAS via

FRAMES Exposure Pathways Modeled 10 10 10 10 10

Population Dose/ Risk Capability 10 6 0 8 6

Dose Factors Used 8.75 7 8.75 3.5 7

Risk Factors Used 8.75 8.75 8.75 0 8.75

Meteorological Data Processing 7.5 7.5 7.5 6 6

Source Term

Calculations 3 3 6 3 3

Verification and

Validation 6.25 6.25 6.25 6.25 5

Ease of Use/ User Friendly 6.25 1.25 5 6.25 1.25

Documentation 5 5 5 5 3

Sensitivity Analysis Capability 0 4 5 0 4

Probabilistic Analysis Capability 0 3 4 0 3

Totals 65.5 61.75 66.25 48 57WA 1-04, Task 3 36 SC&A – August 31, 2010

5.0 REFERENCES

Argonne National Laboratory (ANL), 1998, MILDOS-AREA User’s Guide (Draft), Environmental Assessment Division, September.

Beres, D.A., 1990, The Clean Air Act Assessment Package-1988 (CAP-88) A Dose and Risk Assessment Methodology for Radionuclide Emissions t o the Air , S. Cohen and Associates. Prepared for U.S. Environmental Protection Agency, October.

Eckerman, K.F and Ryman, J.C, 1993, External Exposure to Radionuclides in Air, Water, a nd Soil – Federal Guidance Report No. 12 , U.S. Environmental Protection Agency, EPA-402-R-93-081, September.

Fields, D.E.; Miller, C.W.; Cotter, S.J, 1984, Validation of the AIRDOS-EPA Computer Codes by Simulating Intermediate Range Transport of Kr-85 fr om the Savannah River Plant . Atmos. Environ, 18:2029-2036.

International Commission on Radiological Protection (ICRP), 1996. 1996 Age Dependent Doses from Intakes of Radionuclides , In Annals of the ICRP, Vol. 26, ICRP Publication 72, Pergamon Press, New York.

International Commission on Radiological Protection (ICRP), 1990. 1990 Recommendations of the International Commission on Radiological Protec tion , In Annals of the ICRP, Vol. 21, ICRP Publication 60, Pergamon Press, New York.

International Commission on Radiological Protection (ICRP), 1977, 1977 Recommendations of the International Commission on Radiological Protec tion, In Annals of the ICRP, Vol. 1, ICRP Publication 26, Pergamon Press, New York.

Lehto, M.A., J.C. Courtney, N. Charter, and T. Egan , 2000, “Comparisons of CAP88PC Version 2.0 Default Parameters to Site Specific Inp uts,” Argonne National Laboratory, Waste Management ’00, Session 21, Abstract #397, February 27 to March 2.

Maheras, S.J., P.D. Ritter, P.R. Leonard, and R. Mo ore, 1994, “Benchmarking of the CAP-88 and GENII Computer Codes using 1990 and 1991 Monito red Atmospheric Releases from the Idaho National Engineering Laboratory,” Health Phys ics, 67, pp. 509-517, November.

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